Device and method for treatment of mitral insufficiency

ABSTRACT

A device for treatment of mitral annulus dilatation comprises an elongate body having two states. In a first of these states the elongate body is insertable into the coronary sinus and has a shape adapting to the shape of the coronary sinus. When positioned in the coronary sinus, the elongate body is transferable to the second state assuming a reduced radius of curvature, whereby the radius of curvature of the coronary sinus and the radius of curvature as well as the circumference of the mitral annulus is reduced.

The present invention generally relates to a device and a method fortreatment of mitral insufficiency and, more specifically, for treatmentof dilatation of the mitral annulus.

Mitral insufficiency can result from several causes, such as ischemicdisease, degenerative disease of the mitral apparatus, rheumatic fever,endocarditis, congenital heart disease and cardiomyopathy. The fourmajor structural components of the mitral valve are the annulus, the twoleaflets, the chordae and the papillary muscles. Any one or all of thesein different combinations may be injured and create insufficiency.Annular dilatation is a major component in the pathology of mitralinsufficiency regardless of cause. Moreover, many patients have a mitralinsufficiency primarily or only due to posterior annular dilatation,since the annulus of the anterior leaflet does not dilatate because itis anchored to the fibrous skeleton of the base of the heart.

Studies of the natural history of mitral insufficiency have found thattotally asymptomatic patients with severe mitral insufficiency usuallyprogress to severe disability within five years. At present thetreatment consists of either mitral valve replacements or repair, bothmethods requiring open heart surgery. Replacement can be performed witheither mechanical or biological valves.

The mechanical valve carries the risk of thromboembolism and requiresanticoagulation, with all its potential hazards, whereas biologicalprostheses suffer from limited durability. Another hazard withreplacement is the risk of endocarditis. These risks and other valverelated complications are greatly diminished with valve repair.

Mitral valve repair is theoretically possible if an essentially normalanterior leaflet is present. The basic four techniques of repair includethe use of an annuloplasty ring, quadrangular segmental resection ofdiseased posterior leaflet, shortening of elongated chordae, andtransposition of posterior leaflet chordae to the anterior leaflet.

Annuloplasty rings are needed to achieve a durable reduction of theannular dilatation. All the common rings are sutured along the posteriormitral leaflet adjacent to the mitral annulus in the left atrium. TheDuran ring encircles the valve completely, whereas the others are opentowards the anterior leaflet. The ring can either be rigid, like theoriginal Carpentier ring, or flexible but; non-elastic, like the Duranring or the Cosgrove-Edwards ring.

Effective treatment of mitral insufficiency currently requiresopen-heart surgery, by the use of total cardiopulmonary by-pass, aorticcross-clamping and cardioplegic arrest.

To certain groups of patient, this is particular hazardous. Elderlypatients, patients with a poor left ventricular function, renal disease,severe calcification of the aorta, previous cardiac surgery or otherconcomitant diseases, would in particular most likely benefit from aless invasive approach, even if repair is not complete. The currenttrend towards less invasive coronary artery surgery, withoutcardiopulmonary by-pass, as well as PTCA will also call for adevelopment of a less invasive method for repair of the oftenconcomitant mitral insufficiency.

Therefore, a first object of the present invention is to provide adevice and a method for treatment of mitral insufficiency without theneed for cardiopulmonary by-pass and opening of the chest and heart.

A second object of the invention is to provide reduction of the mitralannulus using less invasive surgery.

These and other objects are attained by a device as defined in theappended claim 1, and by a method as defined in the appended claim 7.

According to the present invention, a device for treatment of mitralisinsufficiency comprises an elongate body having such dimensions as to beinsertable into the coronary sinus and having two states, in a firststate of which the elongate body has a shape that is adaptable to theshape of the coronary sinus, and to the second state of which theelongate body is transferable from the said first state assuming areduced radius of curvature, whereby the radius of curvature of thecoronary sinus is reduced as well as the circumference of the mitralvalve annulus, when the elongate body is positioned in the coronarysinus.

Preferably, means are provided for the transfer of the elongate body tothe second state by bending and/or shortening it from a larger radius ofcurvature to a smaller radius of curvature.

The transfer means may comprise means for bending and/or shortening theelongate body by a preferably asymmetric contraction thereof.

Further, the elongate body may comprise a memory material providing thetransfer to the second state.

In a preferred embodiment, the elongate body may comprise a stent. In analternative embodiment, the device according to the invention maycomprise several stent sections and said.bending and/or shortening meansmay comprise wires for shortening the distance between the stentsections.

According to a second aspect, a method of reducing the circumference ofthe mitral valve annulus comprises the steps of inserting an elongatebody into the coronary sinus in the vicinity of the posterior leaflet ofthe mitral valve, and then providing a bending and/or shortening of theelongate body when positioned in the coronary sinus so as to reduce thecurvature of the coronary sinus and thereby reduce the circumference ofthe mitral valve annulus.

Thus, the present invention takes advantage of the position of thecoronary sinus being close to the mitral annulus. This makes repairpossible by the use of current catheter-guided techniques.

The coronary veins drain blood from the myocardium to the right atrium.The smaller veins drain blood directly into the atrial cavity, and thelarger veins accompany the major arteries and run into the coronarysinus which substantially encircles the mitral orifice and annulus. Itruns in the posterior atrioventricular groove, lying in the fatty tissuebetween the left atrial wall and the ventricular myocardium, beforedraining into the right atrium between the atrial septum and thepost-Eustachian sinus.

In an adult, the course of the coronary sinus may approach within 5-15mm of the medial attachment of the posterior leaflet of the mitralvalve. Preliminary measurements performed at autopsies of adults ofnormal weight show similar results, with a distance of 5.3±0.6 mm at themedial attachment and about 10 mm at the lateral aspect of the posteriorleaflet. The circumference of the coronary sinus was 18.3±2.9 mm at itsostium (giving a diameter of the posterior leaflet of 5.8±0.9 mm) and9.7±0.6 mm along the lateral aspect of the posterior leaflet(corresponding to a diameter of 3.1±0.2 mm).

The invention will be better understood by the following description ofpreferred embodiments referring to the appended drawings, in which

FIG. 1 is a cross-sectional view of a part of a heart,

FIGS. 2 and 3 are schematic views of a first embodiment of a deviceaccording to the present invention,

FIGS. 4-6 are schematic views illustrating an instrument, which may beused when positioning the device shown in FIGS. 2 and 3 in the coronarysinus,

FIG. 7 is a partial, enlarged view of the first embodiment shown in FIG.2.

FIGS. 8 and 9 are schematic views illustrating the positioning of thedevice of FIGS. 2 and 3 in the coronary sinus,

FIGS. 10 and 11 are schematic views illustrating the positioning of asecond embodiment of the device according to the present invention inthe coronary sinus, and

FIGS. 12 and 13 are schematic views illustrating the positioning of athird embodiment of the device according to the present invention in thecoronary sinus.

FIG. 1 is a cross-sectional view through the heart area of the posterioratrioventricular groove 1, which is filled with fatty tissue. It showsthe posterior leaflet 2 of the mitral valve and the adjoining parts 3, 4of the atrial myocardium and the ventricular myocardium. The coronarysinus 5 is shown close to the mitral annulus 6 and behind the attachment7 of the posterior leaflet 2. Since the coronary sinus 5 substantiallyencircles the mitral annulus 6, a reduction of the radius of curvatureof the bent coronary sinus 5 also will result in a diameter andcircumference reduction of the mitral annulus 6.

The device of FIG. 2 comprises an elongate body 8 made of memory metal,e.g. Nitinol, or other similar material which has a memory of anoriginal shape, illustrated in FIG. 3, and can be temporary forced intoanother shape, illustrated in FIG. 2. This elongate body 8 comprisesone, two or more memory metal strings 9 of helical or other shape so asto fit together and be able of permitting the movements described below.Along the elongate body 8 several hooks 10 are fastened so as to extendradially out therefrom. These hooks 10 are covered by a cover sheet 11in FIG. 2.

The elongate body 8 is forced into a stretched or extended state bymeans of a stabilising instrument 12 shown in FIG. 4. This instrument 12has two arms 13 at a distal end 14 of a rod is and a locking means 16 ata proximal end of the rod 15. The distance between the ends of the rod15 corresponds to the desired length of the elongate body 8 when beinginserted into the coronary sinus 5.

The arms 13 are free to move between the position shown in FIG. 4 and aposition in alignment with the rod 15, as shown in FIG. 6. The lockingmeans 16 has two locking knobs 17, which are pressed radially outwardsfrom the rod 15 by two spring blades 18. Thus, the elongated body 8 canbe pushed over the rod 15 of the stabilising instrument 12, thenstretched between the arms 13 and the knobs 17, and finally locked inits stretched state on the stabilising instrument 12 between the arms 13and the knobs 17, as illustrated in FIG. 5.

The rod 15 may be a metal wire which is relatively stiff between thedistal end 14 and the locking means 16 but still so bendable that itwill follow the shape of the coronary sinus 5. Proximally of the lockingmeans 16 the metal wire of the stabilising instrument 11 is more pliableto be able to easily follow the bends of the veins.

The above-described elongate body 8 is positioned in the coronary sinus5 in the following way:

An introduction sheet (not shown) of synthetic material may be used toget access to the venous system. Having reached access to the venoussystem, a long guiding wire (not shown) of metal is advanced through theintroduction sheet and via the venous system to the coronary sinus 5.This guiding wire is provided with X-ray distance markers so that theposition of the guiding wire in the coronary sinus 5 may be monitored.

The elongate body 8 is locked onto the stabilising instrument 12, asshown in FIG. 5, and introduced into the long cover sheet 11 ofsynthetic material. This aggregate is then pushed through theintroduction sheet and the venous system to the coronary sinus 5 ridingon the guiding wire. After exact positioning of the elongate body 8 inthe coronary sinus 5, as illustrated in FIG. 8 where the mitral valve 19is shown having a central gap 20, the cover sheet 11 is retractedexposing the elongate body 8 within the coronary sinus 5. This manoeuvreallows the hooks 10 on the elongate body 8 to dig into the walls of thecoronary sinus 5 and into the heart. The elongate body 8 is still lockedon to the stabilising instrument 12 such that the hooks 10 engage thewalls of the coronary sinus 5 in the stretched or extended state of theelongate body 8.

A catheter 21, shown in FIG. 6, is pushed forward on the guiding wireand the rod 15 for releasing the elongate body 8 from the locking means16 by pressing the spring blades 18 towards the rod 15. This movementreleases the knobs 17 as well as the arms 13 from engagement with theelongate body 8 which contracts as illustrated in FIG. 9 and as a resultbends towards the mitral valve annulus 6 moving the posterior partthereof forward (shown by arrows in FIG. 9). This movement reduces thecircumference of the mitral valve annulus 6 and thereby closes thecentral gap 20.

FIG. 7 illustrates a part of an arrangement of the wires 9 and the hooks10 along a peripheral part of the elongate body 8, whereby the elongatebody 8 will be asymmetrically contracted resulting in a bending thereofwhen interconnecting parts 22 of at least some of the hooks 10 areshortened to an original shape.

FIGS. 10 and 11 illustrate an alternative embodiment of an elongate body8′, which is a solid wire in the shape of an open U-shaped ring thatwill engage the wall of the coronary sinus 5 most adjacent to the mitralvalve annulus 6 when inserted into the coronary sinus 5. The elongatebody 8′ consists of a memory metal material which when reverting to itsoriginal shape will bend as illustrated in FIG. 11. The return of theopen ring 8′ to its original shape may be initiated in several ways, asis obvious to the man skilled in the art.

The third embodiment of the elongate body 8″, illustrated in FIGS. 12and 13, comprises three stent sections 23-25 positioned at one end ofthe elongate body 8″, at the middle thereof and at the other end of theelongate body 8″, respectively. These stent sections 23-25 may bepositioned in the coronary sinus 5 as illustrated by conventional means,such that their positions are fixed. They are connected by wires 26, 27,which may be manoeuvred from outside the vein system such that thedistances between the adjacent stent sections 23, 24 and 24, 25 arereduced. More specifically, these distances are reduced asymmetrically,i.e. more on the side of coronary sinus 5 most adjacent to the posteriorpart of the mitral valve annulus 6. Thereby, the elongate body 8″ isbent, as illustrated in FIG. 13, and presses the coronary sinus 5against the mitral valve annulus 6 closing the gap 20.

Concludingly, the present invention provides a device placed in thecoronary sinus, designed to reduce the dilatation of the mitral annulus.This device is at a distance from the attachment of the posteriorleaflet that does not much exceed the distance at which presentannuloplasty rings are placed by open surgery techniques, and thecoronary sinus is along its entire course large enough to hold such adevice. The device could be positioned by catheter technique or anyother adequate technique and offers a safer alternative to the currentopen surgery methods. The device could be designed or heparincoated soas to avoid thrombosis in the coronary sinus, thus reducing the need foraspirin, ticlopedine or anticoagulant therapy.

It is to be understood that modifications of the above-described deviceand method can be made by people skilled in the art without departingfrom the spirit and scope of the invention.

1-10. (Cancelled).
 11. A device for treating tissue near a valve tomodify flow through the valve, comprising: an elongate body having acentral region and at least two anchoring regions on opposing endportions of the central region, wherein each anchoring region isconfigured to be anchored to opposing areas of tissue against oradjacent to an annulus of the valve and urge the areas of tissue towardsone another; the elongate body being further configured for deliverythrough a catheter to the tissue whereby the elongate body has a firstshape during the delivery and a second shape after the delivery.
 12. Thedevice of claim 11 wherein the tissue comprises an annulus of cardiactissue surrounding the valve.
 13. The device of claim 11 wherein thevalve comprises a cardiac valve.
 14. The device of claim 11 wherein thecentral region comprises a continuous alternating length.
 15. The deviceof claim 11 wherein each of the anchoring regions comprise a fastener.16. The device of claim 11 the elongate body being interwoven such thata plurality of spaces are defined therebetween in the second shape. 17.The device of claim 11 further comprising a biocompatible fastener forattaching each of the anchoring regions to the tissue.
 18. The device ofclaim 17 wherein the biocompatible fastener comprises a distal end and aproximal end, the proximal end defining a projection for securing theanchoring region, and the distal end being configured for attachment tothe tissue.
 19. The device of claim 11 wherein the elongate body isconfigured to approximate a portion of periphery defined by the valve,the central region comprising an accurate length whereby each of theanchoring regions is in apposition to each other.
 20. The device ofclaim 19 wherein the portion of the periphery approximated by theelongate body comprises at least about 50%.
 21. The device of claim 19wherein each of the anchoring regions is biased towards the centralregion.
 22. The device of claim 11 wherein the elongate body comprisesNickel-Titanium alloy.
 23. The device of claim 11 wherein the elongatebody is at least partially coated with a coating layer.
 24. The deviceof claim 11 wherein the catheter comprises an elongate tubular memberhaving a distal end and a proximal end with a lumen therebetween, thedistal end defining a delivery port configured to pass the elongate bodytherethrough.
 25. The device of claim 24 wherein the catheter furthercomprises a stylet having a distal end and a proximal end with a lengththerebetween, the stylet being slidingly disposed in the lumen and beingmanipulatable from its proximal end.
 26. The device of claim 25 whereinthe stylet distal end is angled.
 27. The device of claim 25 wherein thecatheter further comprises a linear advancement mechanism connected tothe proximal end of the stylet.
 28. A method for treating tissue near avalve to modify flow through the valve, comprising: providing anelongate body having a central region, a first anchoring region, and asecond anchoring region, each of the anchoring regions being attached toopposing end portions of the central region; placing a delivery catheternear the tissue; urging the elongate body through a distal openingdefined in the catheter such that the first anchoring region exits thedistal opening and attaches to a first area of the tissue against oradjacent to an annulus of the valve; and further urging the elongatebody through the distal opening such that the second anchoring regionexits the distal opening and attaches to a second area of the tissueagainst or adjacent to the annulus of the valve such that the first areaand the second area are urged towards one another by the elongate body.29. The method of claim 28 wherein the tissue comprises an annulus ofcardiac tissue surrounding the valve.
 30. The method of claim 28 whereinthe valve comprises a cardiac valve.
 31. The method of claim 28 furthercomprising providing a biocompatible fastener for attaching the firstand the second anchoring regions to the first and the second areas oftissue.
 32. The method of claim 28 wherein the elongate body iscomprised of a shape memory alloy.
 33. The method of claim 32 whereinthe shape memory alloy comprises Nickel-Titanium alloy.
 34. The methodof claim 28 wherein the first anchoring region forms a shape configuredfor attachment to the first area of the tissue upon exiting the distalopening.
 35. The method of claim 28 wherein the second anchoring regionforms a shape configured for attachment to the second area of the tissueupon exiting the distal opening.
 36. The method of claim 28 wherein thefirst area and the second area are located about 1800 apart.
 37. Themethod of claim 28 wherein urging the elongate body through the distalopening defined in the catheter comprises advancing a stylet having adistal end and a proximal end with a length therebetween through thedelivery catheter to urge the elongate body.
 38. The method of claim 37wherein the stylet distal end is angled.
 39. The method of claim 37wherein the stylet is advanced by a linear advancement mechanismconnected at the proximal end of the stylet.